β-arrestin2 Affects Cardiac Progenitor Cell Survival through Cell Mobility and Tube Formation in Severe Hypoxia

Abstract

Background and Objectives: beta-arrestin2 (beta-arr2) basically regulates multiple signaling pathways in mammalian cells by desensitization and internalization of G-protein coupled receptors (GPCRs). We investigated impacts of beta-arr2 on survival, mobility, and tube formation of cardiac progenitor cells (CPCs) obtained from wild-type (WT) mouse (CPC-WT), and beta-arr2 knock-out (KO) mouse (CPC-KO) cultured in presence or absence of serum and oxygen as non-canonical roles in GPCR system. Methods: CPCs were cultured in Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12-based media containing fetal bovine serum and growth factors. Survival of 2 types of CPCs in hypoxia and/or serum deprivation was measured by fluorescence-activated cell sorting. Wound healing ability, and tube formation ability on Matrigel of 2 kinds of CPCs were compared in normoxic and hypoxic cultures. Protein expression related to survival and mobility were measured with the Western blot for each culture conditions. Results: CPC-KO showed significantly worse mobility in the wound healing assay and in tube formation on Matrigel especially in hypoxic culture than did the CPC-WT. Also, CPC-KO showed significantly higher apoptosis fraction in both normoxic and hypoxic cultures than did the CPC-WT. Expression of proteins associated with cell survival and mobility, e.g., protein kinase B (Akt), beta-catenin, and glycogen synthase kinase-3 beta (GSK-3 beta) was significantly worse in CPC-KO. Conclusions: The CPC-KO had significantly worse cell mobility, tube formation ability, and survival than the CPC-WT, especially in the hypoxic cultures. Apparently, beta-arr2 is important on CPC survival by means of mobility and tube formation in myocardial ischemia.